So how did it work? Successful to say the least... To be honest, I half expected boatloads of smoke or an explosion as soon as I fired it up because of my lack of electrical knowledge, inability to solder worth a damn, and tendency to mess up the simplest things. Thankfully, after a quick test, my welder and I are still alive to write this post...Wow, what a difference with the capacitor.

I set up a quick lap weld with some 1/8" flat stock, took a deep breath and turned on my welder (disregard my beat-up, junk yard welding table top...I have been laying beads on it and grinding them off in an attempt to get it flat-ish):

Apparently I am too new to this forum to embed my pictures or something, the code is right, oh well...pic number 1 below

Seeing no smoke, I set to Max 2, Wire speed 3ish (anticipating faster wire speed as reported by some who have done this mod), and double checked my .045 tip and trimmed the .035 flux core wire I had in the machine. All still seemed well so I laid my first bead without the capacitor...it was a bit rocky since I am a weekend warrior and it was my first weld this weekend... but workable. Wire speed seemed right, not unreasonably faster than previously but this setting probably would have been too slow previously:

...pic number 2 below

Anxious to try the cap, I flipped the switch and cringed but still no sparks flying. Leaving the settings the same I laid my first bead with the capacitor:

...pic number 3 below

It surprised me just how different it all sounded and felt. More hissing rather than popping, you can see it startled me so much that it affected my bead consistency Amazingly different look to the bead too, and I felt like I had to move a little faster. Surely I can lay a better bead than that with my new found power though:

...pic number 4 below

Much better...that looks amazing actually. Well, for me at least. Love the little v's...never seen those before except on other people's welds...I could probably still stand to slow down a touch more but...

OK, one more without the capacitor...switch back to off.

...pic number 5 below

Well that actually looks pretty decent too...but maybe colder than the previous one? Hard to tell. The sound and feel was definitely better with the cap turned on though, just got to get used to it. Maybe some penetration testing is in order...to be continued.

PS...Weld critiques/recommendations are ALWAYS welcome and encouraged...I know I have a lot to learn and don't offend easily.

 

Penetration testing...didn't work out as well as I had hoped. I don't have the right chemicals for a quick etch. I cut the stock perpendicular to the weld with my dry cut and flap disc-ed down to a shiny finish with a 60 grit flap disc... soaked the ends in white vinegar for several hours and here are the results posted below in the same order I laid the beads: Crappy No Cap #1, Crappy With Cap #1, Decent With Cap #2, Decent No Cap #2.

You can oh-so-barely make out the penetration lines in real life, they kinda-sorta cam out in pics 1-3. I'll let them soak over night and try to get clearer pics tomorrow, maybe.

Anyway, I'm surprised at the lack of penetration that I can see in any of them...pretty sure there is less in the no cap welds than those with the cap, but I'd like to turn up the wire speed (and corresponding amps) and slow down to see if I can get better penetration (with or without). Really, I think the results of this test probably has more to do with my lack of skill than the ability of the welder to penetrate. Maybe more testing tomorrow...I know a video of the difference was requested in another thread...might be able to make that happen if there is demand.

 

For more penetration, try holding the torch at more of a right angle to the weld surface.
I looks like you are leaning the gun too far back as you push the bead.

A little higher wire speed would help also.
You might take a look at this.
http://www.weldingtipsandtricks.com/mig-welding-technique-horizontal.html

 

Forgive my ignorance, but what is the main benefit of adding a capacitor to this 170 welder? I have a new black model 171 that HF warrantied out for me as a replacement unit when my blue 151 model smoked to a stop one day. I REALLY like this new 171 over the 151. Seems to have plenty of heat for anything up to 1/4" plate that I've welded together. If anything, the only thing that I did that really helped the wire speed consistency was stop buying 2lb spools and switch to the 10lb units. I set the spool preload to light with the knob, and it feels much better when laying a bead (no surging in speed like the small spools).

I'm tempted to do the capacitor upgrade since it seems other models from Hobart and Miller have this standard in their 180/190/210 models, correct?

One last question: Since several modders have commented that the arc tends to sputter for a few seconds until the cap is powered up, what would the result of not installing the bleed resistor? The wire would be hot 100% of the time, after the trigger is released? Would this allow the capacitor to remain charged and provide a nice hot start each time?

 

One last question: Since several modders have commented that the arc tends to sputter for a few seconds until the cap is powered up......

If you want to get rid of the startup sputter COMPLETELY....install the time-delay relay modification. You will find all the details in the 151 mod thread.

 

The capacitor mod seems to add about 25% more heat to the welder on each step,and stabilize the arc.

The capacitor charges in less than 1/120th of a second.
I have never noticed anything but the usual momentary hesitation as the arc establishes.

 

Bluewelders, thanks for the confirmation. I plan to order the cap and bleed resistor from digikeys this week then. I see 10ga wire is recommended for the connections. Can you or Takirc02 confirm my connection plans for a permanent upgrade to the capacitor:

100,000uf/50V capacitor:
(+) terminal to bottom bolt of positive (left) plate of rectifier
(-) terminal to bottom bolt of negative (right) plate of rectifier

50ohm/25W bleed resistor:
(+) terminal to bottom bolt of positive (left) plate of rectifier
(-) terminal to bottom bolt of negative (right) plate of rectifier
(plan to bolt to bottom of case for heat dissipation)

Is this correct?

 

The plates usually have small plus and minus stickers on them.
On mine the positive plate is the inner one toward the transformer.
The negative one is next to the fan.

 

Awesome. Thank you all for your help! I'll post pictures of the completed mod and some test beads. I really like this new HF welder. I hope this mod is the icing on the cake until I decide to drop $800~$1000 on a Hobart 190 or 210MVP.

 

Ditto what Galaxieman said. The time delay relay makes a big difference in the start up arc. Also just wait til you ditch the flux core and go to GMAW. You'll love the results.

 

Dave, I'm using shielding gas currently. I used the flux core wire for exactly one session, and tossed it back in my tool chest as emergency only. What a spatter-fest.

 

I used the flux core wire for exactly one session ... What a spatter-fest.

I'm gradually zeroing in on getting low-splatter results after several years of occasional use.

This weld was with a 94056 (Blue 90A AC flux welder, 5 years ago model). I looked to see what sort of FC wire gave me this low-splatter result and discovered I had put the original HF wire back in it - K-kng brand or something like that. Apparently low splatter is as much finding the right settings as it is the brand of wire. This is the lowest-splatter weld I've ever made with it.

Please excuse the amateurish welding technique - I weld infrequently and never practice before a project. In this case I welded 'ears' on a sleeve so I could pin the sleeve to the back of the tractor. Ugly I know, but my welds stay welded. I've never had one break. This is the sort of project I bought the 90A welder to do and splatter is harmless. One light pass with the grinder and one with the wire brush, and almost no splatter remains.

I think what reduced the splatter this time was working with very short stick-out and low wire speed. (0.30 FC wire on Hi amp setting).

 

Amen to the spatter fest. 2 minute weld, 10 minute clean up

 

If you don't mind messing about with the torch.
You can usually shim the gas valve so that a light touch on the trigger will start the gas flow,and pressing slightly harder will start the arc.

 

Question about wiring the bleed resistor: Is there a polarity to it, or doesn't matter which side I wire to the positive side of the rectifier bridge? I know there is a (+) and (-) on the cap, and they must be wired to the pos and neg on the bottom of the rectifier correctly.

(Edited to say: Wiki says resistors have no polarity, but just checking to be sure in this case of the unit in question)

 

Wiki is right,,, for once. Resistors don't care which way they are wired in.

 

Success. All I can say is OUTSTANDING! I used about 18" of #10 THHN wire from Home Depot to wire the cap and resistor in. I didn't have an spare 1/4" x 1" bolts and nuts in my tool box, so I used the two existing connectors on the top of the bridge rectifier.

My welder's operating sounds are louder and it has a much more aggressive sizzle to it. I also noticed as you all predicted the power of the unit went up a whole setting. What used to take Max1 and WS of 7.5 to get good penetration and bead profile is now easily done on Min2 with a WS of about 9.5. I'm going to pic up a new 10lb spool of .035 wire and practice on some 3/16" and 1/4" scrap I have.

Here's a few pics of my setup:

 

Looks good.
Just remember to watch the duty cycle,it is easy to get carried away.

 

Question: Is a 'motor start capacitor' intended for a well pump etc, suitable for this application? (I see a box of them cheap on Craigslist).

 

Bluewelders,
Thinking of adding in this cutoff to the back of my case and wiring it inline with the cap/resistor to keep the ability of the lower power for sheet metal. Would 100amps (rating of cutoff) be adequate?

http://www.grainger.com/Grainger/BATTERY-DOCTOR-Battery-Disconnect-Switch-4NGU6?Pid=search

 

The capacitor won't add more than 25% on any settings,so on a 50amp setting it would only have 12-15 amps through the switch.
On the 120 amp setting it would be 25-30 amps.
So just a large toggle with 10gauge wire should be enough.

 

Thanks for the advice on the switch. I found a 25amp toggle switch at AutoZone, and use the remaining #10 THHN to mount it inside the panel near the wire feed. Works great. Now I have the best power and flexibility to turn it off for sheet metal work when needed.

 

I replaced the power cable with a 10-3 sjoow, removed the ground and replaced it with a longer 2/0 welding cord and 300 amp Bernard ground clamp, I removed the wire feeder and mig gun and used a 2/0 power cord with a female LC-40 to hook up my 400 amp Gililland wire feeder.

Its a pretty good unit imo. Here is a bead while trying to dial it in. I probably won't get the capacitor mod. Its Min - 2 and "42" on my wire feeder.

 

When wiring the toggle switch in between the positive plate on the rectifier and positive end of the capacitor, which side is considered the line (power in) and load (power out)? Or does it even matter in this application?

I also noticed that there is already a 4d151k Varistor wired between the two rectifier plates on my version of this welder, does I still need to install the resistor also?

I'm also a little freaked out by how close these little things are to touching. Is there any reason they would be so close to each other, should I try and spread them a bit further apart?

 

"When wiring the toggle switch in between the positive plate on the rectifier and positive end of the capacitor, which side is considered the line (power in) and load (power out)? Or does it even matter in this application?"

Does not matter...the current goes to the capacitor when charging and from the capacitor during discharge.

"I also noticed that there is already a 4d151k Varistor wired between the two rectifier plates on my version of this welder, does I still need to install the resistor also?"

The Varistor does NOT replace the function of the bleed resistor. I think that the Varistor's function is to 'satisfy' FCC requirements for suppression of radio frequency emissions from the welder. You could remove it and the welder would work fine.

"I'm also a little freaked out by how close these little things are to touching. Is there any reason they would be so close to each other, should I try and spread them a bit further apart? "

Close is OK. Remember that the voltage is 'low' so that there is no danger of arcing across the gap. It takes roughly 5000 volts to arc across 1/4 inch. The voltage in the welder is less than 100 volts in that area.

 

Just added the cap to mine, and wow is all I can say. Completely different machine. No splatter, and just a nice even flow to everything.

 

OK, I have a few questions for the electronic guru's. I just started my "re-learning" to weld program, am just picked up a HF black 170 amp-240 volt mig. I got it for $180.00 and added the 2 year warranty for $40.00.

First question.......What mods apply to this unit?
Second question......Can they be done so that there reversible? (in case it dies and I use the warranty)

I'm not to keen on electrical and cant read electrical diagrams, but I can follow directions.

 

Just the large capacitor and 50 ohm resistor.
If you don't need the low power settings,you do not need the cut out switch.

 

I'll will need the low power for body sheet metal, so I would do the cut out switch. I was going to move the power cord to the rear, so I can use the hole in the front for the switch. Will I have the wire feed "after run" issues that the 151 has after adding the capacitor? Will the wire feed "stabilizer" mod work on the 170?